Novel compounds and methods

ABSTRACT

The present invention relates to use of particular substituted heterocycle fused gamma-carbolines as described herein, in free, pharmaceutically acceptable salt or prodrug form, and pharmaceutical composition comprising the same optionally in combination with one or more agents, for the prophylaxis or treatment of one or more disorders associated with dementia, particularly behavioral or mood disturbances (e.g., agitation/aggression), psychosis, depression and sleep disturbances among others in patients suffering from dementia.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Nos. 61/624,293, 61/624,292 and 61/624,291, all filed on Apr. 14, 2012; and U.S. Provisional Application Nos. 61/671,723 and 61/671,713, both filed on Jul. 14, 2012, the contents of each of which are incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to use of particular substituted heterocycle fused gamma-carbolines as described herein, in free, pharmaceutically acceptable salt or prodrug form, and pharmaceutical composition comprising the same, optionally in combination with one or more agents, for the prophylaxis or treatment of one or more disorders associated with dementia, particularly behavioral or mood disturbances (e.g., agitation/aggression), psychosis, depression and/or sleep disturbances among other disorders in patients suffering from dementia.

BACKGROUND OF THE INVENTION

Dementia is a disorder characterized by the loss of cognitive abilities affecting memory, reasoning, judgment and behavior. At an early stage of dementia, people may experience mild cognitive impairment (MCI, also known as incipient dementia, or isolated memory impairment) which is cognitive impairment beyond that expected based on the age and education of the individual, but which is not significant enough to interfere with their daily activities. Studies suggest that these individuals tend to progress to probable Alzheimer's disease at a rate of approximately 10% to 15% per year. Alzheimer's disease is the most common type of dementia and is an irreversible, progressive neurodegenerative disease that disrupts memory, perception, reasoning, judgment, information processing, emotional behavior, personality as well as social and occupational functions. Of date, 5.4 million of Americans are believed to be living with Alzheimer's and nearly 36 million people worldwide are believed to be living with this disease or other dementias.

Currently, there is no cure or standard of treatment for dementia. Available treatments are palliative and symptomatic in nature aiming to manage and slow the progression of the cognitive manifestation of the disease. Drugs approved in the United States for the treatment of Alzheimer's disease, which is also used to treat dementia in general include acetylcholinesterase inhibitors (e.g., Tacrine, rivastigmine (Exelon), donepezil (Aricept), and galantamine (Razadyne, formerly called Reminyl)) and NMDA receptor antagonist (e.g., memantine (Namenda)). While these drugs improve mental function (such as memory, attention, social interaction, reasoning ability, language ability, and ability to perform activities of daily living), they often cause side effects including stomach upset, diarrhea, nausea, vomiting, muscle cramps, fatigue, difficulty falling or staying asleep or excess sleepiness, depression, bradycardia and other side effects. In addition, these drugs do not treat affective symptoms and/or other behavior disruptions such as mood swing, agitation, aggressive/assaultive behavior and paranoia which are common in dementias. In fact, some studies have shown that memantine, a drug approved for Alzheimer's disease and often used for dementias in general, may have some adverse effects on neuropsychiatric functioning, particularly agitation/aggression, delusions or hallucinations. These untreated and sometimes aggravated behavioral disruptions often prevent the patients from integrating back into society, causing further distress to the caregivers and eventually leading to the patients' institutionalization. To control aggression and psychosis in dementia, particularly in Alzheimer's disease, antipsychotic drugs are used. However, antipsychotic drugs such as haloperidol, risperidone and quetiapine are associated with serious side effects including extrapyramidal side effects (akinesia or akathisia), bone marrow suppression, seizure, orthostatic hypotension, insomnia, sedation, somnolence and weight gain. Many atypical antipsychotic agents also have a higher risk of heart failure. Therefore, the use of these antipsychotic agents in combination with anticholinesterase inhibitor or NMDA receptor antagonist is undesirable.

In addition to behavior and mood disturbances, many dementia patients, particularly those at a more serious stage of the disease also commonly experience sleep disturbances wherein the patients either have difficulty falling asleep, maintaining sleep or experience changes in their sleep-wake cycle/pattern. These patients may also feel restless or agitated in the late afternoon or early evening (often called “sundowning”). In fact, studies have shown evidence that a loss in the suprachiasmatic nucleus (SCN) neuronal population coincides with Alzheimer's patients' stage of dementia. This loss of SCN neuronal population appears to be causative in the observed disturbances in melantonin rhythm which may underlie accompanying sleep disturbances. While agents such as temazepam (Restoril), zolpidem (Ambien), or zaleplon (Sonata), or sedating antidepressants, such as trazodone (Desyrel, Molipaxin), may be useful in managing insomnia, failure of these drugs to improve sleep quality in addition to the associated risk of falling due to drowsiness and psychomotor impairment caused by these agents render them undesirable for dementia, particularly Alzheimer's patients.

There remains an urgent need for an effective therapeutic regime for the prophylaxis or treatment of dementia and disorders associated thereof, particularly to alleviate behavioral/mood disturbances (e.g., agitation, aggressive/assaultive behavior) and sleep disturbances in patients suffering from dementia.

Substituted heterocycle fused gamma-carbolines are known to be agonists or antagonists of 5-HT2 receptors, particularly 5-HT2A and 5-HT2C receptors, in treating central nervous system disorders. These compounds have been disclosed in U.S. Pat. Nos. 6,548,493; 7,238,690; 6,552,017; 6,713,471; RE39,680, and RE39,679, as novel compounds useful for the treatment of disorders associated with 5-HT2A receptor modulation such as obesity, anxiety, depression, psychosis, schizophrenia, sleep disorders, sexual disorders, migraine, conditions associated with cephalic pain, social phobias, and gastrointestinal disorders such as dysfunction of the gastrointestinal tract motility. PCT/US08/03340 and U.S. Pat. No. 7,081,455 also disclose methods of making substituted heterocycle fused gamma-carbolines and uses of these gamma-carbolines as serotonin agonists and antagonists useful for the control and prevention of central nervous system disorders such as addictive behavior and sleep disorders. WO 2009/145900 discloses use of specific compounds of substituted heterocycle fused gamma-carbolines for the treatment of a combination of psychosis and depressive disorders as well as sleep, depressive and/or mood disorders in patients with psychosis or Parkinson's disease. These references, however, do not teach use for the treatment or prophylaxis of disorders associated with dementia, particularly behavioral or mood disturbances such as agitation, irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts and psychosis and sleep disorders associated with dementia.

SUMMARY OF THE INVENTION

It has been discovered that the Compounds of the Invention (i.e., the Compounds of Formula I as described hereinbelow) fully saturate 5-HT_(2A) receptors at a low dose. Altered serotonergic function has consistently been implicated in the pathophysiology of aggression. In animal models, 5-HT_(2A) antagonists attenuate aggressive & impulsive behaviors. Human platelet 5-HT_(2A) levels are associated with aggression in personality disordered patients, but not in healthy control subjects. Postmortem studies also show that 5-HT_(2A) receptor expressions in prefrontal cortical regions are correlated positively with lifetime aggression in subjects who committed suicide. Orbitofrontal 5-HT_(2A) receptor availability is greater in patients with current physical aggression compared with patients without current physical aggression and healthy control subjects. Specific genetic polymorphisms of 5-HT_(2A) receptors are associated with aggression and impulsivity. These Compounds also exhibit efficacy in reducing behavioral disturbances such as agitation and irritability as well as sleep disturbances and symptoms of depression and psychosis. Due to their low off target receptor interactions, the Compounds of the Invention have reduced sedation, cognitive impairment, motor impairment and lower risk of falls. Therefore, Compound of Formula I as described below are effective in treating 5-HT_(2A) related disorders without having the extrapyramidal side effects, psychomotor sedation, cognitive impairment or cardiovascular safety issues such as QTc prolongation. This discovery gives the Compounds of the current Invention particular utility in the treatment or prophylaxis of one or more disorders associated with dementia, particularly behavioral or mood disturbances such as agitation, irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts and sleep disturbances, which conditions are often left untreated by current marketed drugs, as well as psychosis and depressive disorders in dementia patients.

Therefore, in the first aspect, the invention provides a method (Method I) for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, comprising administering to a patient in need thereof, a therapeutically effective amount of a compound of Formula I:

-   -   wherein:     -   X is —N(H)—, —N(CH₃)— or —O—;     -   Y is —C(═O), —C(H)(OH) or —C(H)(OR₁);     -   R₁ is —C(O)—C₁₋₂₁alkyl (e.g., —C(O)—C₁₋₅alkyl, —C(O)—C₆₋₁₅alkyl         or —C(O)—C₁₆₋₂₁alkyl), preferably said alkyl is a straight         chain, optionally saturated or unsaturated and optionally         substituted with one or more hydroxy or C₁₋₂₂alkoxy (e.g.,         ethoxy) groups, for example R₁ is —C(O)—C₆alkyl, —C(O)—C₇alkyl,         —C(O)—C₉alkyl, —C(O)—C₁₁alkyl, —C(O)—C₁₃alkyl or —C(O)—C₁₅alkyl         wherein such compound hydrolyzes to form the residue of a         natural or unnatural, saturated or unsaturated fatty acid, e.g.,         the compound hydrolyzes to form the hydroxy compound on the one         hand and octanoic acid, decanoic acid, dodecanoic acid,         tetradecanoic acid or hexadecanoic acid on the other hand),         in free, pharmaceutically acceptable salt or prodrug form.

In a further embodiment, the invention provides the following formulae:

-   -   1.1. Method I, wherein X in the compound of Formula I is —N(H)—,         —N(CH₃)— or —O—;     -   1.2. Method I or 1.1, wherein X in the compound of Formula I is         —N(H);     -   1.3. Method I or 1.1, wherein X in the compound of Formula I is         —N(CH₃)—;     -   1.4. Method I or 1.1, wherein X in the compound of Formula I is         —O—;     -   1.5. Method I or any of formulae 1.1-1.4, wherein Y in the         compound of Formula I is —C(═O), —C(H)(OH) or —C(H)(OR₁);     -   1.6. Method I or any of formulae 1.1-1.4, wherein Y in the         compound of Formula I is —C(═O);     -   1.7. Method I or any of formulae 1.1-1.4, wherein Y in the         compound of Formula I is —C(H)(OH);     -   1.8. Method I or any of formulae 1.1-1.4, wherein Y in the         compound of Formula I is —C(H)(OR₁);     -   1.9. Method T or 1.8, wherein R₁ is —C(O)—C₁₋₂₁alkyl (e.g.,         —C(O)—C₁₋₅alkyl, —C(O)—C₆₋₁₅alkyl or —C(O)—C₁₆₋₂₁alkyl),         preferably said alkyl is a straight chain, optionally saturated         or unsaturated and optionally substituted with one or more         hydroxy or C₁₋₂₂alkoxy (e.g., ethoxy) groups, for example R₁ is         —C(O)—C₆alkyl, —C(O)—C₇alkyl, —C(O)—C₉alkyl, —C(O)—C₁₁alkyl,         —C(O)—C₁₃alkyl or —C(O)—C₁₅alkyl wherein such compound         hydrolyzes to form the residue of a natural or unnatural,         saturated or unsaturated fatty acid, e.g., the compound         hydrolyzes to form the hydroxy compound on the one hand and         octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic         acid or hexadecanoic acid on the other hand);     -   1.10. Method I or 1.8, wherein R₁ is —C(O)—C₆₋₁₅alkyl, e.g.,         —C(O)—C₉alkyl;     -   1.11. Method I or 1.8, wherein R₁ is —C(O)—C₁₋₅alkyl, e.g.,         —C(O)—C₃alkyl;     -   1.12. Method I or any of formulae 1.1-1.5 or 1.7, wherein the         Compound is:

-   -   1.13. Method I or any of formulae 1.1-1.5 or 1.7, wherein the         Compound is:

-   -   1.14. Method I or any of formulae 1.1-1.5 or 1.7, wherein the         Compound is:

-   -   1.15. Method I or any of formulae 1.1, 1.3, 1.5 or 1.7, wherein         the Compound is:

-   -   1.16. Method I or any of formulae 1.1, 1.3, 1.5 or 1.6, wherein         the Compound is:

-   -   1.17. Method I or any of formulae 1.1, 1.3, 1.5, 1.8 or 1.9,         wherein the Compound is:

-   -   1.18. Method I or any of formulae 1.1, 1.3, 1.5, 1.8 or 1.9,         wherein the Compound is:

-   -   in free, pharmaceutically acceptable salt or prodrug form.

In a further embodiment of the first aspect, the invention provides Method I as follows:

-   -   2.1. Method I or any of 1.1-1.18, wherein the disorders         associated with dementia are disorders associated with         Huntington's disease, Parkinson's disease, Mulitple sclerosis,         Amyotrophic lateral sclerosis, Down syndrome, Elderly         depression, Wernicke-Korsakoff's syndrome, corticobasal         degenerations, and prion disease;     -   2.2. Method I or any of 1.1-1.18, wherein the disorders         associated with dementia are disorders associated with mild         cognition impairment and dementing illnesses including senile         dementia, Alzheimer's disease, Pick's disease, frontotemporal         dementia, parasupranculear palsy, dementia with Lewy bodies and         vascular dementia;     -   2.3. Method I or any of 1.1-1.18 or 2.1, wherein the disorders         associated with dementia are disorders associated with senile         dementia, Alzheimer's disease, Pick's disease, frontotemporal         dementia, parasupranculear palsy, dementia with Lewy bodies and         vascular dementia;     -   2.4. Method I or any of 1.1-1.18 or 2.1, wherein the disorders         associated with dementia are disorders associated with         Alzheimer's disease;     -   2.5. Method I or any of 1.1-1.18 or 2.1, wherein the disorders         associated with dementia are disorders associated with mild         cognition impairment;     -   2.6. Method I or any of 1.1-1.18 or 2.1-2.5, wherein the         disorder associated dementia to be treated is selected from the         group consisting of (1) behavioral or mood disorders such as         agitation/irritation, aggressive/assaultive behavior, anger,         physical or emotional outbursts; (2) psychosis; (3) depression;         and (4) sleep disorders in patients suffering from dementia,         particularly Alzheimer's disease;     -   2.7. Method T or any of 1.1-1.18 or 2.1-2.6, wherein the         disorder to be treated is psychosis in a patient with dementia,         particularly Alzheimer's disease;     -   2.8. Method I or any of 1.1-1.18 or 2.1-2.7, wherein the         disorder to be treated is depression in a patient with dementia,         particularly Alzheimer's disease;     -   2.9. Method I or any of 1.1-1.18 or 2.1-2.8, wherein the dosage         of the Compound of Formula I, or any of 1.1-1.18 is 10-100 mg;     -   2.10. Method I or any of 1.1-1.18 or 2.1-2.9, wherein the         disorder to be treated is behavioral or mood disorders such as         agitation/irritation, aggressive/assaultive behavior, anger,         physical or emotional outbursts in a patient with dementia,         particularly Alzheimer's disease;     -   2.11. Method I or any of 1.1-1.18 or 2.1-2.10, wherein the         disorder to be treated is sleep disorders in a patient with         dementia, particularly Alzheimer's disease;     -   2.12. Method I or any of 1.1-1.18 or 2.1-2.11, wherein the         disorder to be treated is sleep maintenance insomnia, frequent         awakenings, and waking up feeling unrefreshed in a patient with         dementia, particularly Alzheimer's disease;     -   2.13. Method I or any of 1.1-1.18 or 2.1-2.12, wherein the         disorder to be treated is sleep maintenance insomnia in a         patient with dementia, particularly Alzheimer's disease;     -   2.14. Method I or any of 1.1-1.18 or 2.1-2.12, wherein the         disorder to be treated is advanced sleep-phase syndrome in a         patient with dementia, particularly Alzheimer's disease;     -   2.15. Method I or any of 1.1-1.18 or 2.1-2.12, wherein the         disorder to be treated is delayed sleep-phase syndrome in a         patient with dementia, particularly Alzheimer's disease;     -   2.16. Method I or any of 1.1-1.18, 2.1-2.6 or 2.10-2.15, wherein         the dosage of the Compound of Formula I, or any of 1.1-1.18 is         1-10 mg;     -   2.17. Method I or any of 1.1-1.18 or 2.1-2.16, further comprises         administering one or more therapeutic agents useful for the         prophylaxis or treatment of dementia, particularly Alzheimer's         disease;     -   2.18. Method I or any of 1.1-1.18 or 2.17, wherein the         therapeutic agent useful for the prophylaxis or treatment of         dementia, particularly Alzheimer's disease is a cholinesterase         inhibitor (e.g., acetylcholinesterase inhibitor) or an N-Methyl         D-Asparate (NMDA) receptor antagonist, in free or         pharmaceutically acceptable salt form;     -   2.19. Method I or any of 1.1-1.18 or 2.17-2.18, wherein the         cholinesterase inhibitor (e.g., acetylcholinesterase inhibitor)         is selected from the group consisting of Tacrine, rivastigmine         (Exelon), donepezil (Aricept), and galantamine (Razadyne,         formerly called Reminyl)) in free or pharmaceutically acceptable         salt form;     -   2.20. Method I or any of 1.1-1.18 or 2.17-2.19, wherein the         cholinesterase inhibitor (e.g., acetylcholinesterase inhibitor)         is donepezil in free or pharmaceutically acceptable salt form;     -   2.21. Method I or any of 1.1-1.18 or 2.17-2.18, wherein the NMDA         receptor antagonist is memantine in free or pharmaceutically         acceptable salt form;     -   2.22. Method I or any of 1.1-1.18 or 2.17-2.18, wherein the         therapeutic agent useful for the prophylaxis or treatment of         dementia, particularly Alzheimer's disease is a combination of a         cholinesterase inhibitor (e.g., acetylcholinesterase inhibitor)         and an N-Methyl D-Asparate (NMDA) receptor antagonist, in free         or pharmaceutically;     -   2.23. Method I or any of 1.1-1.18 or 2.22, wherein the one or         more therapeutic agent(s) useful for the prophylaxis or         treatment of dementia, particularly Alzheimer's disease or         symptoms thereof is a combination of donepezil and memantine in         free or pharmaceutically acceptable salt form.     -   2.24. Method I or any of the foregoing methods further comprises         administering one or more therapeutic agents selected from         antidepressant compounds, compounds that modulate GABA activity         (e.g., enhances the activity and facilitates GABA transmission),         a GABA-B agonist, a 5-HT modulator (e.g., a 5 HT_(1A) agonist, a         5-HT_(2A) antagonist, a 5-HT_(2A) inverse agonist, etc.), a         melatonin agonist, an ion channel modulator (e.g., blocker), a         serotonin-2 antagonist/reuptake inhibitor (SARIs), an orexin         receptor antagonist, an H3 agonist, a noradrenergic antagonist,         a galanin agonist, a CRH antagonist, human growth hormone, a         growth hormone agonist, estrogen, an estrogen agonist, a         neurokinin-1 drug, and an antipsychotic agent, e.g., an atypical         antipsychotic agent, in free or pharmaceutically acceptable salt         form.

In a second aspect, the invention provides a pharmaceutical composition (Pharmaceutical Composition I) comprising the compound of Formula I or any of formulae 1.1-1.18 in combination with one or more therapeutic agents useful for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease in admixture with a pharmaceutically acceptable diluent or carrier.

In a further embodiment of the second aspect, the invention provides the Pharmaceutical Composition I as hereinbefore described wherein the therapeutic agent(s) useful for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, is a cholinesterase inhibitor (e.g., acetylcholinesterase inhibitor) or an N-Methyl D-Asparate (NMDA) receptor antagonist) as described in any of formulae 2.17-2.23.

In another embodiment of the second aspect, the invention provides the Pharmaceutical Composition I as hereinbefore described wherein the therapeutic agent(s) useful for the prophylaxis or treatment of one or more disorders associated with dementia is selected from: antidepressant compounds, compounds that modulate GABA activity (e.g., enhances the activity and facilitates GABA transmission), a GABA-B agonist, a 5-HT modulator (e.g., a 5-HT_(1A) agonist, a 5-HT_(2A) antagonist, a 5-HT_(2A) inverse agonist, etc.), a melatonin agonist, an ion channel modulator (e.g., blocker), a serotonin-2 antagonist/reuptake inhibitor (SARIs), an orexin receptor antagonist, an H3 agonist, a noradrenergic antagonist, a galanin agonist, a CRH antagonist, human growth hormone, a growth hormone agonist, estrogen, an estrogen agonist, a neurokinin-1 drug, and an antipsychotic agent, e.g., an atypical antipsychotic agent, in free or pharmaceutically acceptable salt form.

In a third aspect, the invention provides a pharmaceutical composition comprising the Compound of Formula I or any of formulae 1.1-1.18 in admixture with a pharmaceutically acceptable diluent or carrier, or the Pharmaceutical Composition I as hereinbefore described, for use (in the manufacture of a medicament) for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, as disclosed in Method I or any of formulae 2.1-2.24.

In the fourth aspect, the invention provides use of the Compound of Formula I or any of formulae 1.1-1.18 (in the manufacture of a medicament) for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., one or more disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, as disclosed in Method I or any of formulae 2.1-2.24.

In the fifth aspect, the invention provides the Pharmaceutical Composition of the Invention as described herein for use in the manufacture of a medicament for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease as disclosed in Method I or any of formulae 2.1-2.24.

DETAILED DESCRIPTION

The Compounds of the Invention as hereinbefore described have a selective receptor profile wherein they fully saturate the 5-HT_(2A) receptors at a low dose and also bind to dopamine receptors and serotonin reuptake transporter (SERT) at a higher dose. Therefore the Compounds of the Invention are effective in treating one or more disorders associated with dementia, e.g., one or more disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, particularly behavioral/mood disturbances (e.g., agitation, aggressive/assaultive behavior) and sleep disorders, which are inadequately treated by the current marketed drugs for dementia and Alzheimer's disease, as well as treating psychosis and depressive disorders in patients suffering from dementia. The compounds of the Invention (i.e., Formula I as hereinbefore described) may be used in a combination therapy wherein the Compound of Formula I may be administered simultaneously, separately or sequentially with another active agent to treat dementia or dementing illnesses as hereinbefore described, particularly Alzheimer's disease or symptoms thereof.

The Compound of Formula I, in free, pharmaceutically acceptable salt or prodrug form may be administered in a composition, wherein said Compound of Formula I as hereinbefore described in free, pharmaceutically acceptable salt or prodrug form, is in admixture with a pharmaceutically acceptable diluent or carrier. Wherein the Compound of Formula I is administered in a combination therapy, the combination may be administered as a fixed combination (wherein the therapeutic agents are in a single dosage form, e.g., the Pharmaceutical Composition I hereinbefore described) or as a free combination (wherein therapeutic agents are in a separate dosage form).

The second or further therapeutic agents useful for the prophylaxis or treatment of dementia as hereinbefore described, particularly Alzheimer's disease described in Method I or any of formulae 2.17-2.24 of the invention include but not limited to a cholinesterase inhibitor and/or N-Methyl D-Asparate (NMDA) receptor antagonist.

Cholinesterase inhibitors, e.g., acetylcholinesterase inhibitors, are known in the art and/or are described e.g., in U.S. Pat. Nos. 4,895,841; and 4,948,807, the contents of each of which are incorporated by reference in their entirety. Preferred cholinesterase inhibitors to be used with the compound of the present invention include donepezil, rivastignmine, galantamine and tacrine.

NMDA receptor antagonists are also known in the art and are described in U.S. Pat. No. 5,061,703, the contents of which are incorporated by reference in their entirety. Preferred NMDA receptor antagonist to be used with the compound of the present invention is memantine.

Unlike dopamine receptor antagonists, Compounds of Formula I normalize brain dopamine activity, particularly in the prefrontal cortex. The Compounds of Formula I bind to 5-HT_(2A) and dopamine D₂ receptors. Compounds of Formula I also exhibit nanomolar binding affinity for SERT compared to known antidepressants. Therefore, the compounds of Formula I are useful for the treatment of (1) behavioral or mood disorders such as agitation/irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts; (2) psychosis; (3) depression; and (4) sleep disorders in patients suffering from dementia, particularly Alzheimer's disease. Therefore, in addition to the therapeutic agents useful for the treatment of dementia, the methods of the invention as hereinbefore described may optionally further comprises one or more therapeutic agents selected from antidepressant compounds, compounds that modulate GABA activity (e.g., enhances the activity and facilitates GABA transmission), a GABA-B agonist, a 5-HT modulator (e.g., a 5-HT_(1A) agonist, a 5-HT_(2A) antagonist, a 5-HT_(2A) inverse agonist, etc.), a melatonin agonist, an ion channel modulator (e.g., blocker), a serotonin-2 antagonist/reuptake inhibitor (SARIs), an orexin receptor antagonist, an H3 agonist, a noradrenergic antagonist, a galanin agonist, a CRH antagonist, human growth hormone, a growth hormone agonist, estrogen, an estrogen agonist, a neurokinin-1 drug, and an antipsychotic agent, e.g., an atypical antipsychotic agent, in free or pharmaceutically acceptable salt form. In such methods, the therapeutic agents may be adjunctive to the compounds of the invention. As used herein the term “adjunctive” refers to any treatment that is used in conjunction with another to increase the chance of cure, or to increase the first treatment's efficacy. In other words, adjunctive therapy acts as an aid to the primary treatment. The combinations of the invention can include mixtures of the combined drugs, as well as two or more separate compositions of the drugs, which individual compositions can be, for example, co-administered together to a patient at the same of different times.

The antidepressant useful for the invention may be selected from amitriptyline, amoxapine, bupropion, citalopram, clomipramine, desipramine, doxepin, duloxetine, escitaloprame, fluoxetine, fluvoxamine, imipramine, isocarboxazid, maprotiline, mirtazapine, nefazodone, nortriptyline, paroxetine, phenelzine sulfate, protiptyline, sertraline, tranylcypromine, trazodone, trimipramine, and velafaxine, in free or pharmaceutically acceptable salt form. In certain embodiment, the antidepressant(s) is a selective serotonin reuptake inhibitor (SSRI). In a further embodiment, the SSRI compound is selected from the group consisting of citalopram, escitalopram oxalate, fluoxetine, fluvoxamine maleate, paroxetine, sertraline, and dapoxetine, in free or pharmaceutically acceptable salt form.

The dosages of a compound of Formula I and/or the antidepressant of Method I can be the same as or lower than the approved dosage for the drug, the clinical or literature test dosage or the dosage used for the drug as a monotherapy. For example the daily dosage of compound of Formula I to be administered in combination with an antidepressant is about 1 mg to about 140 mg, in another embodiment about 1 mg to about 100 mg, in another embodiment about 10 mg to about 100 mg, in another embodiment about 10 mg to about 50 mg, in another embodiment about 10 mg to about 40 mg, in another embodiment about 20 mg to about 40 mg and in another embodiment about 1 mg to about 10 mg. The amount of antidepressant to be administered in combination with the compound of Formula I is about 0.01 mg to about 2000 mg, in another embodiment about 0.1 mg to about 200 mg, in another embodiment about 10 mg to about 200 mg. In particular embodiments, the additional therapeutic agent, e.g., the antidepressant SSRI is sertraline and the daily dosage of sertraline is between about 20 mg and 100 mg.

In a specific embodiment, the dosages of a compound of Formula I and/or the second therapeutic agents are lower than when used in a monotherapy. Therefore, in a particular embodiment, the daily dosage of a compound of Formula I is lower than 100 mg once daily, or less than 50 mg, or less than 40 mg, or less than 30 mg, or less than 20 mg, or less than 10 mg. In another preferred embodiment, the dosages of both the Compound of Formula I and the antidepressant agent are lower than the dosages used for the individual drug as a monotherapy. Therefore, in a particular embodiment, for example, Method I comprises administering (1) a Compound of Formula I at a dosage lower than 100 mg once daily, preferably less than 50 mg, more preferably less than 40 mg, still more preferably less than 30 mg, still more preferably less than 20 mg, still more preferably less than 10 mg; and (2) antidepressant, for example a SSRI such as sertaline, at a daily dosage of less than 50 mg, more preferably, less than 20 mg, still more preferably, less than 10 mg, most preferably less than 6 mg, in free or pharmaceutically acceptable salt form.

The term “GABA” refers to gamma-aminobutyric acid. The GABA compounds are compounds which bind to the GABA receptor, and include, but are not limited to one or more of doxepin, alprazolam, bromazepam, clobazam, clonazepam, clorazepate, diazepam, flunitrazepam, flurazepam, lorazepam, midazolam, nitrazepam, oxazepam, temazapam, triazolam, indiplon, zopiclone, eszopiclone, zaleplon, Zolpidem, gabaxadol, vigabatrin, tiagabine, EVT 201 (Evotec Pharmaceuticals) or estazolam.

5HT_(2A) antagonists include ketanserin, risperidone, eplivanserin, volinanserin (Sanofi-Aventis, France), pruvanserin, pimavanserin (ACP-103), MDL 100907 (Sanofi-Aventis, France), HY10275 (Eli Lilly), APD125 (Arena Pharmaceuticals, San Diego, Calif.), AVE8488 (Sanofi-Aventis, France) and pizotifen.

5HT_(1A) agonists include repinotan, sarizotan, eptapirone, buspirone and MN-305 (MediciNova, San Diego, C.A).

Melatonin agonists include melatonin, ramelteon (ROZEREM®, Takeda Pharmaceuticals, Japan), VEC-162 (Vanda Pharmaceuticals, Rockville, Md.), PD-6735 (Phase II Discovery and agomelatine.

Ion channel blockers such as lamotrigine, gabapentin or pregabalin.

Orexin receptor antagonists include orexin, a 1,3-biarylurea, SB-334867-a (GlaxoSmithKline, UK), GW649868 (GlaxoSmithKline) and a benzamide derivative, for example.

Serotonin-2 antagonist/reuptake inhibitors (SARI) include Org 50081 (Organon-Netherlands), ritanserin, nefazodone, serzone and trazodone.

Neurokinin-1 drugs include Casopitant (GlaxoSmithKline).

Specific examples of additional therapeutic agents useful for the current invention include modafinil, armodafinil, doxepin, alprazolam, bromazepam, clobazam, clonazepam, clorazepate, diazepam, flunitrazepam, flurazepam, lorazepam, midazolam, nitrazepam, oxazepam, temazapam, triazolam, indiplon, zopiclone, eszopiclone, zaleplon, zolpidem, gabaxadol, vigabatrin, tiagabine, EVT 201 (Evotec Pharmaceuticals), estazolam, ketanserin, risperidone, eplivanserin, volinanserin (Sanofi-Aventis, France), pruvanserin, pimavanserin (ACP-103), pizotifen, MDL 100907 (Sanofi-Aventis, France), HY10275 (Eli Lilly), APD125 (Arena Pharmaceuticals, San Diego, Calif.), AVE8488 (Sanofi-Aventis, France), repinotan, sarizotan, eptapirone, buspirone, MN-305 (MediciNova, San Diego, Calif.), melatonin, ramelteon (ROZEREM®, Takeda Pharmaceuticals, Japan), VEC-162 (Vanda Pharmaceuticals, Rockville, Md.), PD-6735 (Phase II Discovery), agomelatine, lamotrigine, gabapentin, pregabalin, orexin, a 1,3-biarylurea, SB-334867-a (GlaxoSmithKline, UK), GW649868 (GlaxoSmithKline), a benzamide derivative, Org 50081 (Organon-Netherlands), ritanserin, nefazodone, serzone, trazodone, Casopitant (GlaxoSmithKline), amitriptyline, amoxapine, bupropion, citalopram, clomipramine, desipramine, doxepin, duloxetine, escitaloprame, fluoxetine, fluvoxamine, imipramine, isocarboxazid, maprotiline, mirtazapine, nefazodone, nortriptyline, paroxetine, phenlzine sulfate, protiptyline, sertraline, tranylcypromine, trazodone, trimipramine, velafaxine, chlorpromazine, haloperidol, droperidol, fluphenazine, loxapine, mesoridazine molidone, perphenazine, pimozide, prochlorperazine promazine, thioridazine, thiothixene, trifluoperazine, clozapine, aripiparazole, olanzapine, quetiapine, risperidone, ziprasidone and paliperidone, asenapine, lurasidone, iloperidone and cariprazine, in free or pharmaceutically acceptable salt form.

The compounds of Formula I and their pharmaceutically acceptable salts and salt crystals may be made using the methods as described and exemplified in any of the following patents or applications: U.S. Pat. Nos. 6,548,493; 7,238,690; 6,552,017; 6,713,471; U.S. RE39,680; RE39,679; PCT/US08/03340; U.S. application Ser. No. 10/786,935; WO 2009/114181 and WO 2011/133224, the contents of each of which are incorporated by reference in their entirety. If not commercially available, starting materials for these processes may be made by procedures, which are selected from the chemical art using techniques which are similar or analogous to the synthesis of known compounds. All references cited herein are hereby incorporated in their entirety by reference.

The words “treatment” and “treating” are to be understood accordingly as embracing prophylaxis and treatment or amelioration of symptoms of disease and/or treatment of the cause of the disease. In particular embodiment, the word “treatment” and “treating” refers to prophylaxis or amelioration of symptoms of the disease.

The term “patient” may include a human or non-human patient.

The term “dementia” is intended to refer to a condition or disorder characterized by the loss of cognitive ability affecting memory, thinking, language, judgment and behavior. Early symptoms of dementia may include difficulty performing tasks that require some thought (balancing a checkbook, playing games (such as bridge); learning new information; getting lost on familiar routes; having language difficulties (difficulties in finding name of familiar objects); losing interest in things previously enjoy; losing social skills. More severe symptoms of dementia include change in sleep patterns, often waking up at night; difficulty performing basic tasks such as brushing teeth or preparing a meal; forgetting details about current events; having hallucinations, violent behavior, delusions, depression, agitation; difficulty reading or writing; having poor judgment or loss of ability to recognize danger; losing the ability to recognize family members or understand language. The term “dementia” refers to any of the dementing illnesses as described herein regardless of etiology and therefore shall include but not limited to mild or severe cognition impairment and dementing illnesses such as senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease. In a particular embodiment, dementia refers to mild cognitive impairment. In another embodiment, dementia refers to Alzheimer's disease.

The term “disorder associated with dementia” means common co-morbid psychiatric disorders or conditions associated with dementia, which include but not limited to (1) behavioral or mood disorders such as agitation/irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts; (2) psychosis; (3) depression; and (4) sleep disorders. In particular embodiment of the invention, the disorders associated with dementia are disorders associated Alzheimer's disease.

The term “mild cognitive impairment” or “mild cognition impairment” (MCI, also known as incipient dementia, or isolated memory impairment) is cognitive impairment beyond that expected based on the age and education of the individual, but which is not significant enough to interfere with their daily activities. Symptoms of MCI include difficulty performing more than one task at a time, solving problems or making decisions, forgetting recent events or conversations and taking longer to perform more difficult mental activities.

If not otherwise specified or clear from context, the following terms herein have the following meanings:

-   -   a. “Alkyl” as used herein is a saturated or unsaturated         hydrocarbon moiety, e.g., one to twenty-one carbon atoms in         length, which may be linear or branched (e.g., n-butyl or         tert-butyl), preferably linear, unless otherwise specified. For         example, “C₁₋₂₁ alkyl” denotes alkyl having 1 to 21 carbon         atoms. In one embodiment, alkyl is optionally substituted with         one or more hydroxy or C₁₋₂₂alkoxy (e.g., ethoxy) groups. In         another embodiment, alkyl contains 1 to 21 carbon atoms,         preferably straight chain and optionally saturated or         unsaturated, for example R₁ is an alkyl chain containing 1 to 21         carbon atoms, preferably 6-15 carbon atoms, 16-21 carbon atoms,         e.g., so that together with the —C(O)— to which it attaches,         e.g., when cleaved from the compound of Formula I, forms the         residue of a natural or unnatural, saturated or unsaturated         fatty acid.

Compounds of the Invention refer to Compounds of Formula I, which include any of formulae 1.1-1.18, in free, salt or prodrug form. For example, where the compounds contain acidic substituents, in base addition salt form or where the compounds contain a basic substituent, in acid addition salt form. The Compounds of the Invention are intended for use as pharmaceuticals, therefore pharmaceutically acceptable salts are preferred. Salts which are unsuitable for pharmaceutical uses may be useful, for example, for the isolation or purification of free Compounds of the Invention or their pharmaceutically acceptable salts, are therefore also included. Pharmaceutically acceptable salts include, for example, the hydrochloride and tosylate salts. Where dosage amounts of salts are given by weight, e.g., milligrams per day or milligrams per unit dose, the dosage amount of the salt is given as the weight of the corresponding free base, unless otherwise indicated.

Compounds of the Invention may in some cases also exist in prodrug form. A prodrug form is compound which converts in the body to a Compound of the Invention. For example when the Compounds of the Invention contain hydroxy or carboxy substituents, these substituents may form physiologically hydrolysable and acceptable esters. As used herein, “physiologically hydrolysable and acceptable ester” means esters of Compounds of the Invention which are hydrolysable under physiological conditions to yield acids (in the case of Compounds of the Invention which have hydroxy substituents) or alcohols (in the case of Compounds of the Invention which have carboxy substituents) which are themselves physiologically tolerable at doses to be administered. For example, wherein Y of the compound of Formula I is —C(H)(OR₁), and R₁ is —C(O)—C₁₋₂₁ alkyl, e.g., —C(O)—C₃alkyl or —C(O)—C₉alkyl, these compounds may hydrolyze under physiological condition to yield a compound of Formula I wherein Y is —C(H)(OH) on the one hand and C₁₋₂₁alkyl-C(O)OH, e.g., C₃alkyl-C(O)OH or C₉alkyl-C(O)OH on the other hand. As will be appreciated the term thus embraces conventional pharmaceutical prodrug forms. Wherein a prodrug (e.g., the compound of formula (I) wherein R₁ is —C(O)—C₁₋₂₁alkyl) is used, the dosage amount is calculated based on the amount of the compound of formula (I) wherein Y is C(═O) in free base form.

The term “simultaneously” when referring to a therapeutic use means administration of two or more active ingredients at or about the same time by the same route of administration.

The term “separately” when referring to a therapeutic use means administration of two or more active ingredients at or about the same time by different route of administration.

The phrase “disorder(s) associated with Alzheimer's disease” includes, but is not limited to (1) behavioral or mood disorders such as agitation/irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts; (2) psychosis; (3) depression; and (4) sleep disorders in patients suffering from Alzheimer's disease.

Dosages employed in practicing the present invention will of course vary depending, e.g. on the particular disease or condition to be treated, the particular Compound of the Invention used, the mode of administration, and the therapy desired. Unless otherwise indicated, an amount of the Compound of the Invention for administration (whether administered as a free base or as a salt form) refers to or is based on the amount of the Compound of the Invention in free base form (i.e., the calculation of the amount is based on the free base amount). Wherein a prodrug (e.g., the compound of formula (I) wherein R₄ is —C(O)—C₁₋₂₁alkyl) is used, the dosage amount is calculated based on the amount of the compound of formula (I) wherein Y is C(═O) in free base form. Compounds of the Invention may be administered by any suitable route, including orally, intra-muscularly, subcutaneously, parenterally or transdermally, but are preferably administered orally. Compounds of the Invention may be administered by any suitable route, including orally, parenterally or transdermally, but are preferably administered orally.

In general, satisfactory results for Method I and any of formulae 2.1-2.23 for the treatment or prophylaxis of various disorders associated with dementia such as a combination of at least behavioral disorders such as aggressive/assaultive behavior, anger, physical or emotional outbursts; sleep disorders; mood disorders such as agitation/irritation; depression; and/or psychosis in a patient suffering from dementia, particularly Alzheimer's disease, as set forth above are indicated to be obtained on oral administration at dosages of the order from about 1 mg to 100 mg to 140 mg once or more than once daily, preferably 2.5 mg-60 mg, e.g., 2.5 mg, 5 mg, 10 mg, 20 mg, 30 mg, 40 mg, 50 mg or 60 mg, once daily of the compound of Formula I or any of formulae 1.1-1.18 in free, pharmaceutically acceptable salt or prodrug form, preferably via oral administration. Satisfactory results for Method I and any of formulae 2.1-2.24 for the treatment of sleep disorders and/or behavioral or mood disorders alone such as aggressive/assaultive behavior, anger, physical, emotional outbursts or agitation/irritation in patients with dementia, particularly Alzheimer's disease (e.g., patients without symptoms of psychosis) are indicated to be obtained on oral administration at dosages of the order from about 1-10 mg, e.g., 2.5 mg-5 mg, e.g., 2.5 mg, 3 mg, 4 mg, 5 mg or 10 mg, of a Compound of Formula I or any of formulae 1.1-1.18, in free, pharmaceutically acceptable salt or prodrug form, once daily, preferably via oral administration.

For combination therapy, one skilled in the art can design a combination based on the level of severity (staging) of and/or the symptoms manifested in dementia, particularly Alzheimer's disease to enhance efficacy with reduce side effects. Wherein the symptoms/disorders to be treated are behavioral/mood disorders such as aggressive/assaultive behavior, anger, physical or emotional outbursts and/or agitation/irritation; or sleep disorders, but the patients do not have psychosis, the compound of the invention may be administered at a lower dosage, e.g., about 1-10 mg, e.g., 2.5 mg-5 mg, e.g., 2.5 mg, 3 mg, 4 mg, 5 mg or 10 mg, of a Compound of Formula I or any of formulae 1.1-1.18, in free, pharmaceutically acceptable salt or prodrug form, once or more than once daily, preferably via oral administration. Wherein the symptoms/disorders to be treated are psychosis as well as behavioral/mood disorders such as aggressive/assaultive behavior, anger, physical or emotional outbursts and/or agitation/irritation; or sleep disorders, the compounds of the invention may be administered at a higher dosage, e.g., about 1 mg to 100 mg to 140 mg once daily, preferably 2.5 mg-60 mg, e.g., 20 mg-60 mg, 20 mg-40 mg, e.g., 2.5 mg, 5 mg, 10 mg, 20 mg, 30 mg, 40 mg, 50 mg or 60 mg, once or more than once daily, for example, greater than 20 mg per day, preferably via oral administration.

Dosages of the second or further therapeutic agent(s) useful for the prophylaxis or treatment of dementia, particularly for the prophylaxis or treatment of Alzheimer's disease or symptoms thereof, e.g., cholinesterase inhibitor, e.g., acetylcholinesterase inhibitor or NMDA receptor antagonist can vary in range known to a person skilled in the art. The dosages can range from about 1 mg to 100 mg. In particular embodiments, the compound of the Invention may be combined with the second or further therapeutic agent(s) useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof as follows:

-   -   i) about 5 mg, 10 mg or 23 mg dosage of donepezil, in free or         pharmaceutically acceptable salt form; and/or     -   ii) about 1.5 mg, 2 mg, 3 mg, 4.5 mg, 4.6 mg, 6 mg or 9.5 mg of         rivastigmine, in free or pharmaceutically acceptable salt form;         and/or     -   iii) about 4 mg, 8 mg, 12 mg, 16 mg or 24 mg of galantamine, in         free or pharmaceutically acceptable salt form; and/or     -   iv) about 2 mg, 5 mg, 7 mg, 10 mg, 14 mg, 21 mg or 28 mg of         memantine, in free or pharmaceutically acceptable salt form;         in combination with the Compound of the Invention as         hereinbefore described, in free, pharmaceutically acceptable         salt or prodrug form.

For the avoidance of doubt, any disclosure of a numerical range, e.g., “up to X” amount is intended to include the upper numerical limit X. Therefore, a disclosure of “up to 60 mg” is intended to include 60 mg.

Pharmaceutical compositions comprising compounds of the Invention may be prepared using conventional diluents or excipients and techniques known in the galenic art. Thus oral dosage forms may include tablets, capsules, solutions, suspensions and the like.

Example 1: Effect of Compound a on Reversal of Social Isolation Resulted from Repeated Stress

Mice are tested for social isolation behavior after repeated exposure (once daily for 10 days) to an aggressive resident intruder mouse in the social defeat/resident intruder paradigm as describe by Berton et al., Science (2006) 311:864-868, the contents of which are incorporated by reference. Mice are then dosed chronically, once daily for 30d, with either vehicle (5% DMSO/5% Tween-20/15% PEG400/75% water, 6.7 ml/kg volume) or Compound A (1 mg/kg, ip) in vehicle solution. On the day after the last drug or vehicle treatment, the mice are placed in the open field in the presence of a resident intruder mouse and the animal's behavior recorded by videotape for 10 min. The videotapes are then scored for the total time each mouse spent during a 10 min period in specified open-field quadrants. The total time (sec) spent by mice representing each drug treatment group in the Interaction Zone in proximity to the resident intruder mouse or, in the Corner Zones, at a distance from the intruder mouse is expressed as a mean (±SEM).

Results: Decreased social function is a core feature of the ‘negative’ symptoms of schizophrenia that are poorly addressed by existing antipsychotic medications. The social defeat/resident intruder model can be used to measure social isolation behavior in rodents. Isolation behavior has been shown to be reversed using this model, after chronic administration of anti-depressant medications with potent SERT activity, including fluoxetine (Berton et al., Science (2006) 311:864-868). Neither acute administration of anti-depressant medications or chronic treatment with anti-anxiety medications, like chlordiazepoxide, are similarly effective in this paradigm (Berton et. al., Science (2006) 311:864-868). Thus, the model has been proposed for the identification of compounds to address social isolation behavior, such as social isolation behavior resulted from repeated stress. This assay is therefore used to demonstrate reversal of social isolation behavior.

In the experiment described or similarly described above, mice are subjected to exposure to an aggressive resident intruder mouse in the social defeat/resident intruder paradigm as described in Berton et al., Science (2006) 311:864-868. They are then dosed chronically, once daily for 30d, with either vehicle or Compound A (1 mg/kg, IP) in vehicle. On the day after the last drug or vehicle treatment the mice are placed in the open field in the presence of a resident intruder mouse and the total time each mouse spent during a 10 min period in defined open-field quadrants in close proximity to the intruder or in isolation to the intruder is measured. As anticipated, exposure to the aggressor mouse significantly reduced the amount of time resident mice spent in proximity to the intruder (p<0.0.05 compared with vehicle). However, mice treated with Compound A following exposure to the intruder paradigm, showed no significant reduction in time spent in proximity to the intruder (NS, compared with Compound A alone). Compound A treatment alone did not result in differences in time spent in the Interaction Zone, compared with untreated control mice. The data indicate that chronic treatment with Compound A results in a reversal of social defeat behavior comparable to that seen after chronic treatment with anti-depressant medications such as fluoxetine. This experiment shows that Compound A is effective in reversing social isolation resulted from repeated stress. This experiment also shows that Compound A has functional anti-depressant activity. 

What I claim is:
 1. A method for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, comprising administering to a patient in need thereof, a therapeutically effective amount of a compound of Formula I:

wherein: X is —N(H)—, —N(CH₃)— or —O—; Y is —C(═O), —C(H)(OH) or —C(H)(OR₁); R₁ is —C(O)—C₁₋₂₁alkyl (e.g., —C(O)—C₁₋₅alkyl, —C(O)—C₆₋₁₅alkyl or —C(O)—C₁₆₋₂₁ alkyl), preferably said alkyl is a straight chain, optionally saturated or unsaturated and optionally substituted with one or more hydroxy or C₁₋₂₂alkoxy (e.g., ethoxy) groups, for example R₁ is —C(O)—C₆alkyl, —C(O)—C₇alkyl, —C(O)—C₉alkyl, —C(O)—C₁₁alkyl, —C(O)—C₁₃alkyl or —C(O)—C₁₅alkyl wherein such compound hydrolyzes to form the residue of a natural or unnatural, saturated or unsaturated fatty acid, e.g., the compound hydrolyzes to form the hydroxy compound on the one hand and octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid or hexadecanoic acid on the other hand), in free, pharmaceutically acceptable salt or prodrug form.
 2. The method according to claim 1, wherein the compound of Formula I is selected from the group consisting of:

in free, pharmaceutically acceptable salt or prodrug form.
 3. The method according to any of claims 1-2, wherein the disorder associated with dementia is a disorder associated with Alzheimer's disease.
 4. The method according to any of claims 1-2, wherein the disorder associated with dementia is a disorder associated with mild cognition impairment.
 5. The method according to any of claims 1-4, wherein the disorder associated with dementia to be treated is selected from the group consisting of (1) behavioral or mood disorders such as agitation/irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts; (2) psychosis; (3) depression; and (4) sleep disorders.
 6. The method according to any of claims 1-4, wherein the disorder associated with dementia to be treated is behavioral or mood disorders such as agitation/irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts.
 7. The method according to any of claims 1-6, wherein the dosage of the Compound of Formula I in free, pharmaceutically acceptable salt or prodrug form is about 10-100 mg.
 8. The method according to any of claims 1-7, wherein the disorder associated with dementia to be treated is behavioral or mood disorders such as agitation/irritation, aggressive/assaultive behavior, anger, physical or emotional outbursts.
 9. The method according to any of claims 1-7, wherein the disorder associated with dementia to be treated is sleep disorders.
 10. The method according to any of claims 8-9, wherein the dosage of the Compound of Formula 1 in free, pharmaceutically acceptable salt or prodrug form is about 1-10 mg.
 11. The method according to any of claims 1-10, further comprises administering one or more therapeutic agents useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof.
 12. The method according to claim 11, wherein the therapeutic agent useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof is an acetylcholinesterase inhibitor or an N-Methyl D-Asparate (NMDA) receptor antagonist.
 13. The method according to claim 11 or 12, wherein the therapeutic agent useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof is selected from the group consisting of Tacrine, rivastigmine, donepezil and galantamine.
 14. The method according to claim 11, 12 or 13, wherein the therapeutic agent useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof is donepezil.
 15. The method according to claim 14, wherein the dosage of the compound according to claim 1 or 2 is about 1-10 mg and the dosage of donepezil is about 5 mg, 10 mg or 23 mg, in free or pharmaceutically acceptable salt form.
 16. The method according to any of claims 11-15, wherein the therapeutic agents useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof are donepezil and memantine.
 17. A pharmaceutical composition comprising the compound of Formula I according to claim 1 or 2, in combination with one or more therapeutic agents useful for the prophylaxis or treatment of one or more disorders associated with dementia (e.g., cholinesterase inhibitor (e.g., acetylcholinesterase inhibitor) or an N-Methyl D-Asparate (NMDA) receptor antagonist), in admixture with a pharmaceutically acceptable diluent or carrier.
 18. The pharmaceutical composition according to claim 17, wherein the therapeutic agent useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof is an acetylcholinesterase inhibitor.
 19. The pharmaceutical composition according to claim 17 or 18, wherein the therapeutic agent useful for the prophylaxis or treatment of dementia, particularly Alzheimer's disease or symptoms thereof is donepezil in free or pharmaceutically acceptable salt form.
 20. A pharmaceutical composition comprising about 1-10 mg of the compound according to claim 1 or 2 and about 5 mg, 10 mg or 23 mg of donepezil, in free or pharmaceutically acceptable salt form, in admixture with a pharmaceutically acceptable diluents or carrier.
 21. A pharmaceutical composition comprising the compound of Formula I, in admixture with a pharmaceutically acceptable diluent or carrier, or the pharmaceutical composition according to any of claims 17-20, (in the manufacture of a medicament) for use in the manufacture of a medicament for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease according to any of claims 1-16.
 22. Use of the compound according to claim 1 or 2 (in the manufacture of a medicament) for the prophylaxis or treatment of one or more disorders associated with dementia, e.g., one or more disorders associated with mild cognition impairment and dementing illnesses including senile dementia, Alzheimer's disease, Pick's disease, frontotemporal dementia, parasupranculear palsy, dementia with Lewy bodies, vascular dementia, Huntington's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Down syndrome, elderly depression, Wernicke-Korsakoff's syndrome, corticobasal degenerations, and prion disease, as disclosed in any of claims 1-16. 